This invention relates to seals for utility meters and the like and, more particularly, to a single-use seal designed to permit easy detection of any tampering whether successful or not.
Seals to discourage tampering with utility meters, shipping containers, boxcars and the like are well known. While such seals are made from a variety of designs, they may be classified generally into two types: multi-use seals and single use seals. Multi-use seals contain a number of parts, including a casing, a shackle adapted for interlocking engagement with the casing and a locking member designed to effect the locking engagement of the shackle with the casing. The locking member of such a seal is usually breakable in some manner, which permits removal of the shackle from locking engagement with the casing and the meter, and reuse of the casing and shackle. Multi-use seals of this construction disclosed in U.S. Pat. No. 998,878 and U.S. Pat. No. 3,980,332 having the same assignee as the present invention.
Single-use seals usually employ a unitary housing comprising the casing and the locking member. After the shackle is locked within the housing, it cannot be removed without destroying the seal. A seal of this general design is disclosed in U.S. Pat. No. 4,353,583. Often, the housing is made of some frangible material, and the seal is broken by shattering the housing with a sharp blow. Seals of this design are disclosed in U.S. Pat. Nos. 511,642 and 367,877.
All of the prior art seals have at least one substantial drawback that limits their utility. Whether a seal is of the multi-use or single-use type, where its housing or casing is composed of an opaque material, the seal may be subject to undetectible tampering. For example, the shackle may be cut flush with the housing or casing to permit removal of the seal. After the meter or the like has been meddled with or reset, the seal may again be installed by reforming the tip of the shackle and reinserting it into the casing or housing.
Even where a seal is made from some transparent material, it may be tampered with without detection. In some cases a continuous tensile force applied to the shackle causes its tips to deform and pull out of the casing or housing of the seal. The shackle may then simply be reformed and reinserted. In other cases a thin rigid member or "pick" may be inserted into the housing or casing to deform the tip of the shackle thus allowing its removal. Again, the tip merely has to be reformed and reinserted.
Where a multi-use seal comprising several parts is employed, cannibalization becomes a serious problem. The seal may be broken, the meter or the like meddled with or reset and the seal reinstalled using parts taken from other seals of the same design.
In certain instances seals have been composed of some frangible material designed to break when the seal is tampered with. While such seals indeed disclose attempts at tampering, they cannot achieve this objective and remain intact.
It is thus an object of the present invention to overcome the disadvantages of the prior art seals by providing a single-use tamper-resistant transparent seal designed to permit easy detection of any tampering and to prevent cannibalization.
It is a further object of the invention to provide such a seal wherein the seal is made from an inexpensive material and is easily installed.